The present invention relates to a new type of stent for transluminal implantation and in particular new vascular stents.
Stents for transluminal implantation are well known. They are generally comprised of metallic supports which are inserted into a part of the human body such as bile ducts, the urinary system, the digestive tube and notably by percutaneous route inside the blood vessels, usually the arteries in which case they are typically termed vascular stents. Stents are usually generally cylindrical and are constructed and arranged to expand radially once in position within the body. They are usually inserted while they have a first relatively small diameter and implanted in a desired area, for example inside a vessel, then the stent is expanded in situ until it reaches a second diameter larger than the first diameter. A balloon associated with the catheter is usually used to provide the necessary interior radial force to the stent to cause it to expand radially. Self-expanding stents are also known which can expand from a first diameter to a larger second diameter without the use of a means for applying an interior radial force, such as a balloon, to them. One such type of self-expanding stent is a stent made of a shape memory metal which expands to its second larger diameter upon exposure to body temperature. Such stents are also known.
The present invention proposes a novel type of stent which combines a self-expanding part or portion with a part or portion which requires an interior radial force for expansion. More specifically, a stent for transluminal implantation according to the present invention will comprise cylindrical parts preferably in juxtaposition, with at least one part being self-expanding whereas another part requires an interior radial force for its expansion, such as a balloon catheter or the like. Basically, the stent will consist of at least two of the aforementioned parts but may consist of more than two parts. Such an arrangement enables improved placement of the stent by providing immediate expansion in part upon release of the stent from its delivery catheter.